The deer hemoglobins are of particular interest because they provide an in vitro model for human sickle cell anemia. Structural and breeding data have indicated that the deer hemoglobin alpha chains differ by point mutations in genes from two different loci, one of which arose from a duplication. The Beta chains are the products of alleles at a single locus but vary by several peptides. Recent studies have demonstrated a marked neonatal increase in 2,3- DPG with a subsequent drop to insignificant levels. Further studies are in progress on the precise structural differences between the Beta chains, the manner in which variations influence hemoglobin function, and erythrocyte morphology. Electron microscopy is one of the tools which is being applied in the latter area.